Purification of benzene using a platinum-containing catalyst



March 3, 19 F. a. CIAPETTA ETAL PURIFICATION OF BENZENE USING A PLATINUM-CONTAINING CATALYST Filed May 21, 1956 0 0 8 I v H 0 l/ .m J E ///I a [q] I l E I R. 4 I II} w M I 6 4 l V II K I F. w .I E I II f M .I/// 2 a 5 w l f 5 I' m I I y l/ III lllfill 0 0 0 0 0 0 0 I .TII w 0 o 7 9 w 5 Z 1 O 4 a Z Ofr m m PAW wmwfli 1K5 m fi r m M I process.

' and commercially feasible.

1. 2,876,268 PURIFICATION OF BENZENE USING A PLATINUM-CONTAINING CATALYST Frank G. Ciapetta, Upper Darby, Pa., and Emil Koft,

In, Woodbury Heights, and Seymour L. Meisel, Woodbury, N. J., assignors to Socony Mobil Oil Company, Inc., a corporation of New York Application May 21, 1956, Serial No. 586,063 3 Claims. (Cl. 260674) rials boil at temperatures very near to that of benzene itself, separation by distillation methods is virtually impossible. Accordingly, resort has been had to various methods, such as, for example, extraction with sulfuric acid. Recoveries, however, are often relatively poor, because of the difficulty in controlling the extraction Processes for the catalytic hydrodesulfurization of hydrocarbon fractions are known. Such processes, however, are disadvantageous for removal of thio- 4 phenic materials from benzene, because, concurrent with the removal of sulfur, there is a tendency to hydrogenate substantial amounts of the benzene to cyclohexane. It has now been found that thiophenic materials can be removed from crude benzene by a process that is simple and commercially feasible. It has been discovered that crude benzene can be purified by hydrogenative treatment in the presence of platinum-containing catalysts, under carefully controlled conditions.

Accordingly, it is an object of thepresent invention to provide a process for the purification of crude benzene. Another object is to provide a method for removing thiophenic materials from crude benzene that is simple A specific object is to provide a method for removing thiophenic materials from crude benzene by means of a hydrogenative treatment that does not appreciably eifect hydrogenation of the benzene. A more specific object is to provide a processv for purifying crude benzene by hydrogenative treatment in the presence of a platinum-containing catalyst, under 1 ;-In general, the present invention provides a method for the removal of thiophenic materials from a benzene United States Patent Patented Mar. 3, 1959 fraction containing thiophenic materials with a platinumcontaining catalyst in the presence of hydrogen in amounts expressed in terms of the mole ratio of hydrogen to hydrocarbon, varying between about 1 to about 20, at pressures varying between about 100 p. s. i. g. and about 1500 p. s. i. g., at a liquid hourly space velocity varying between about 0.1 and about 20, and within a 25-degree temperature range that falls within the range varying between about 400 F. and about 600 F.

The catalysts utilizable herein are platinum-containing catalysts. These catalysts comprise platinum metal in amounts varying between about 0.05 weight percent and about '2 weight percent, preferably 0.1-l percent, by weight of the catalyst, distended upon a carrier. The carriers utilizable include pumice, charcoal, silica, alumina, silica-alumina, silica-alumina-zirconia, aluminaboria and the like. These catalysts can be prepared by any of the methods well known to those skilled in the art. A suitable method involves impregnating the carrier with a platinum compound, such as chloroplatinic acid, calcining the impregnated carrier, and reducing and activating the platinum in the presence of hydrogen.

The process of this invention must be carried out under carefully controlled conditions. In order to insure substantially complete removal of thiophenic materials without hydrogenating the benzene to cyclohexane in any appreciable amounts, the primary process variable that must be controlled is the temperature, as is demonstrated hereinafter. The other process variables, however, must also be controlled to some extent. Accordingly, the pressure will vary between about 100 p. s. i. g. and about 1500 p. s. i. g., preferably between about 200 p. s. i. g. and about 1200 p. s. i. g. The molar ratio of hydrogen to hydrocarbon will vary between about 1 and about 20, preferably between about 4 and about 12. The liquid hourly space velocity utilizable varies between about 0.1 and about 20, and preferably between about 0.5 and about 10.

As will be readily apparent, the process of this invention can be operated feasibly by means of a continuous operation. The process can be carried out in the presence of a moving mass of catalyst or in a fluid operation. It is particularly feasible, however, to carry out the process in the presence of a fixed bed of catalyst or of the so-called fluidized static bed catalyst.

EXAMPLE 1 The charge material used in this example was a mixture of mole percent cyclohexane and 30 mole percent benzene that had suflicient 3-methylthiophene added thereto to make the sulfur content of the charge 0.54 weight percent. In a series of runs, the charge stock was contacted with a catalyst comprising 0.4 weight percent platinum deposited upon alumina (an activated alumina of commerce) and in the presence of hydrogen. The molar ratio of hydrogen to hydrocarbon used was 10, the liquid hourly space velocity was 1, and the hydrogen pressure was 1000 p. s. i. g. Each run was carried out at a different temperature falling within the range varying between about 450 F. and about 800 F. The pertinent data and run results are set forth in Table I.

Table 1 Run A B O D E F G Av. Temperature, F 400 450 525 601 680 761 835 Pressure, p. s. l. g 1,000 1,000 1,000 1,000 1, 000 1, 000- 1, 000 LHSV 1 1 1 1 1 1 1 Hr/hydrocarhon, moles 10 10 10 10 10 '10 10 Benzene conversion, percent 0.7 5. 3 12. 0 38. 9 77. 7- 86. 7 Percent Desullurlzatlon 44. 6 53. 6 96. 9 97. 8 98. 7 98. 1' 99. 8

l Mole percent benzene converted into cyclohexane.

Curves 1' and 2 in the figure are based upon the data set forth in Table I. Curve 1 shows the graphic relationship between the temperature and the mole percent conversion of the benzene into cyclohexane that occurs when 4 ditions used herein. Comparing curves 1 and- 4, 110%- ever, it will be noted that the amount of hydrogenation is appreciably higher in the presence of the catalyst having a higher platinum content. In other words, for the the sulfur-contaminated benzene fraction was treated in 5 particular sulfur content of these runs (0.54 wt. percent), the presence of hydrogen and of the platinum-containing the optimum platinum content is about 0.4 weight percatalyst. Curve 2 presents the graphic relationship becent and 0.6 weight percent is too high. The latter platitween the temperature and the weight percent desulfuri'zanum content in the catalyst would be preferred, however, tion that occurs simultaneously with the hydrogenation when benzene fractions of higher content are charged. set forth in curve 1. It will be noted that at a tempera- In practicin the process of this invention, catalysts are of about 500 F. none of the benzene has been hyother than the platinum-on-alumina catalyst can be used. drogeuated, yet 90 percent of the sulfur had been re- It has been found, however, that not all catalysts are moved therefrom. At a temperature of 525 P. less than substantially equivalent with respect to results. Thus, 5' percent of the benzene had been hydrogenated, whereas for example, catalysts having carriers, such as silica- 98 percent of the sulfur had been removed. At higher 5 alumina may permit as much as 10 to percent hydrotemperatures there is no substantial increase in the amount genation. It has been found, however, that the carriers of desulfurization, but the amount of hydrogenation contemplated herein are effective at temperatures telling commences to rise relatively rapidly. Accordingly, in within the ranges specified hereinbefore. Under the order to obtain feasible purification of the benzene, the conditions of the present process other thiophenic matetemperature must be at least about 500 F. In order to rials are also removed. Accordingly, the process is apavoid the hydrogenation of benzene to an appreciable plicable for the removing of any thiophenic material extent, however, the temperature should not be greater from sulfur-contaminated, benzene-containing fractions than about 525 F. These temperatures, of course, will without appreciably hydrogenating the benzene.

vary slightly at other pressures and liquid hourly space Although the present invention has been described in velocities. Accordingly, the process of this invention is conjunction with preferred embodiments, it is to be uncarried out within a temperature range of about 25 F. derstood that modifications and variations may be rethat falls within the range varying between about 400 sorted to, without departing from the spirit and scopeof F. and about 600 F, and preferably between about this invention, as those skilled in the art will readily 450 F. and about 550 F. The 25-degree operating understand. Such variations and modifications are contemperature band will, as mentioned hereinbefore, shift sidered to be within the purview and scope of the ap- .somewhat within these broad and preferred temperature pended claims.

ranges as the space velocity and the pressure are varied. What is claimed is:

At the higher space velocities, the 25-degree temperature 1. A method for the removalof thiophenic materials band will fall in the upper regions of the range. On the from a benzene fraction containing thiopheniomaterials other hand, higher pressures generally result in moving that comprises contacting said benzene fraction with-a the 25-degree temperature band toward the lower portion platinum-containing catalyst, in the presence of hydrogen of the temperature range. in amounts, expressed in terms of the mole ratio of Another feature of the process of this invention is that hydrogen to hydrocarbon, varying between about 1 and the optimum amount of platinum on the catalyst is someabout 20, at pressures varying between about 100 what dependent upon the amount of thiophenic materials p. s. i. g. and about 1500 p. s. i. g., at a liquid hourly ill the benZeIle, in 011161? minimize the amflllnt of yspace velocity varying between about 0.1 and about 20 drogenation of the benzene. This will be, apparent from d i hin an operating temperature b d f 25 d the following p grees on the Fahrenheit scale falling with the tempera- EXAMPLE 2 ture range varying between about 400 F. and about Using the charge material described in Example 1, 600 3 operatmg'tempoerature baind.bemg between another series of runs was made. The same operating about 500 and about 525 at a hquld hourly sPace conditions used in Example 1 were employed. Instead aboulf 1 and a pressure of abou? 1000 of the 0.4 weight percent platinum-omalumina catalyst, 531d Operating FemPerature band bemg P however, the catalyst used comprised 0.6 weight percent When the hquld hourly Space veloclty 15 lower platinum deposited upon alumina. The pertinent data than about 1 and when the Pressure is greater than about r tforthi T bl II, 1000 p. s. .i. g.; and said operating temperature band Table II Run J' K L M N O P Temperature, F 450 526 605 683 764 847 Pressure, p. s. Lg 1,000 1, 000 1,000 1, 000 1,000 1,000 LHSV" 1 1 1 1 1 1 Hgflrydrocarbou, moles 10 '10 10 1 10 0 Benzene conversion, percent 8. 0 8. 0 8. 0 31. 3 74. 6 94. 9 97. 6 Percent: Desulfurization 0 64. 7 96. 7 98. 3 98. 7 98. 9 98. 7

l Mole percent benzene converted into cyclohexane.

Curves 3 and 4 in the figure are based upon the data being above 500-525 F. when the, liquid hourly space set forth in Table II. Curve 3 shows the graphic relavelocity is greater than about 1 and when the pressure tionship between the temperature and the percent desulis below about 1000 p. s. i. g. furization when the thiophene-containing benzenefraction 2. A method for the removal of thiophenic materials is contacted, in the; presence of hydrogen, with the platifrom a benzene fraction containing thiophenic materials num-on-alurnina catalyst that contains. 0.6, percent platithat comprises contacting said benzene fraction with a vnum by. weight. Curve 4 presents, the concurrent rela- 7,0 catalystv comprising between about 0.1 percent and about tionship between the percent hydrogenation of benzene lpercent, by weight of the catalyst, of platinum deposited to cycloheXane and the temperature. Considering curves upon alumina, in the presence of hydrogen in amounts, '2. and 3, it will be apparent that maximum desulfuriza expressed in terms of the mole ratio of hydrogen to hytion is effected at about 500-525 F. regardless of the 'drocarbon, varying between about 4 and about 12, at 'platinumcontent of'the'catalyst, under the operating con- 7 5 pressures varying between about 200 p. s. i. g. and about 1200 p. s. i. g., at a liquid hourly space velocity, varying between about 0.5 and about 10, and within an operating temperature band of 25 degrees on the Fahrenheit scale that falls within the range varying between about 450 F. and about 550 F.; said operating temperature band being between about 500 F. and about 525 F., at a liquid hourly space velocity of about 1 and a pressure of about 1000 p. s. i. g.; and said operating temperature band being below 500-525 F. when the liquid hourly space velocity is lower than about 1 and when the pressure is greater than about 1000 p. s. i. g.; and said operating temperature band being above 500-525 F. when the liquid hourly space velocity is greater than about 1 and when the pressure is below about 1000 p. s. 1. g.

3. A method for the removal of thiophenic materials from a benzene fraction that contains thiophenic materials that comprises contacting said benzene fraction with a catalyst comprising between about 0.1 percent and about 1 percent, by weight of the catalyst, of platinum deposited upon alumina, in the presence of hydrogen in an amount, expressed in terms of the mole ratio of hydrogen to hydrocarbon, of about 10, at a pressure of about 1000 p. s. i. g., at a liquid hourly space velocity of about 1, and at a temperature varying between about 500 F. and about 525 F.

References (Iited in the file of this patent UNITED STATES PATENTS 

2. A METHOD FOR THE REMOVAL OF THIOPHENIC MATERIALS FROM A BENZENE FRACTION CONTAINING THIOPHENIC MATERIALS THAT COMPRISES CONTACTING SAID BENZENE FRACTION WITH A CATALYST COMPRISING BETWEEN ABOUT 0.1 PERCENT AND ABOUT 1 PERCENT, BY WEIGHT OF THE CATALYST, OF PLATINUM DEPOSITED UPON ALUMINA, IN THE PRESENCE OF HYDROGEN IN AMOUNTS, EXPRESSED IN TERMS OF THE MOLE RATIO OF HYDROGEN TO HYDROCARBON, VARYING BETWEEN ABOUT 4 AND 12, AT PRESSURES VARYING BETWEEN ABOUT 200P.S.I.G. AND ABOUT 1200 P.S.I.G., AT A LIQUID HOURLY SPACE VELOCITY, VARYING BETWEEN ABOUT 0.5 AND ABOUT 10, AND WITHIN AN OPERATING TEMPERATURE BAND OF 25 DEGREES ON THE FAHRENHEIT SCALE THAT FALLS WITHIN THE RANGE VARYING BETWEEN ABOUT 450* F. AND ABOUT 550* F.; SAID OPERATING TEMPERABAND BEING BETWEEN ABOUT 500* F./AND ABOUT 525* F., AT A LIQUID HOURLY SPACE VELOCITY OF ABOUT 1 AND A PRESSURE OF ABOUT 1000 P.S.I.G.; AND SAID OPERATING TEMPERATURE BAND BEING BELOW 500-525* F. WHEN THE LIQUID HOURLY SPACE VELOCITY IS LOWER THAN ABOUT 1 AND WHEN THE PRESSURE IS GREATER THAN ABOUT 1000 P.S.I.G.; AND 